PhD Thesis - staffweb - University of Greenwich

PhD Thesis by John Ewer.3.4.4 Use as part of ongoing research program (involving others)The fact that the prototype system was to be used as a research framework for CFD techniqueshad important implications for the use of the legacy software. One such consideration was thatthe new algorithm syntax and data access mechanisms could not be too "alien" in usage to theintended developers. Another consideration was for the research requirements, within themedium to long term, that would have implications on the form of data structures used and themodularity of the software.3.4.5 Data structuresThe form of the data structures used in the legacy software had to be evaluated so that thefunctional and data dependencies were known prior to any re-design. It was also necessary toassess the nature and extent of data passing mechanisms. This evaluation ended with anassessment of the most flexible and extensible data structures that could be used in the targetsystem which were still compatible with the algorithms within the legacy software.3.4.6 Performance issuesCFD code users are highly aware of the overheads of performance because the size andcomplexity of simulations, together with the computationally intensive numerical CFDprocessing, lead to extended run-times. When the legacy software was re-designed someconsideration had to be given to the performance degradation or improvement that would resultfrom any design changes or implementation differences.3.4.7 Portability issuesSince there is generally no specific computer hardware that is used to run CFD simulations then,in order to provide adequate user coverage, the software was developed to be as portable aspossible. This affected the choice of implementation language and the choice of third party3-36